Removal of perfluoroalkyl and polyfluoroalkyl substances in potable reuse systems

Abstract

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a group of persistent contaminants that have been identified throughout the aquatic environment. In this study, ten targeted perfluoroalkyl acids (PFAAs), three targeted PFAA precursors, and non-targeted PFAA precursors were monitored in four full- and pilot-scale potable reuse plants at each stage of advanced treatment. Non-targeted PFAA precursors were quantified by applying a total oxidizable precursor assay in which PFAA precursors are oxidized by hydroxyl radicals to targeted PFAAs. Two of the potable reuse systems had membrane-based treatments with reverse osmosis and UV-advanced oxidation (RO-UV/AOP) and two used ozone, biological activated carbon filtration and granular activated carbon adsorption (O-BAC-GAC). The total targeted PFAAs in the four tertiary effluents, the influent sources for the potable reuse systems, ranged from 52 to 227 ng/L with non-targeted PFAA precursors accounting for 30-67% of total PFASs on a molar basis. The RO-UV/AOP treatment trains reduced PFAAs and PFAA precursors to below their method reporting limits through the barrier provided by RO. The O-BAC-GAC based treatment trains reduced, but did not completely remove PFAAs or PFAA precursors and the PFASs present in the product water were primarily shorter-chain PFAAs, some of which lack human health guidance values for drinking water. The relative fraction of targeted shorter-chain PFAAs increased after each treatment step indicating that there was preferential removal of the PFAA precursors and longer-chain PFAAs. This study provides new insight on the concentrations and treatment of PFAA precursors through potable reuse treatment systems.

Trace and bulk organics removal during ozone–biofiltration treatment for potable reuse applications

“…Ozone-/biofiltration-based AWT trains have been studied locally and elsewhere (Blackbeard et al, 2015;Bourgin et al, 2018;Glover, Quiñones, & Dickenson, 2018;Knopp, Prasse, Ternes, & Cornel, 2016;Kumar et al, 2017;Lee, Howe, & Thomson, 2012;Maidrand & Ohlinger, 2013;Reungoat et al, 2012;Sun et al, 2018;Sundaram & Emerick, 2010a;Zhu, Wang, & Wieland, 2015). A compilation of CEC removal results from eleven recent wastewater ozone-biofiltration studies from locations around the world is summarized in Table 2.…”

“…Ethinyl estradiol (EE2) and 17-β-estradiol are expected to be removed by the secondary biological treatment processes with at least 10 days mean cell residence time (compared to 15 days maintained at STMWRF; Clara, Kreuzinger, Strenn, Gans, & Kroiss, 2005). Others have reported PFOS in filtered secondary effluent at a MRL of 1.85 ng/L, but none was detected at STMWRF (Glover et al, 2018).…”

“…They also confirmed that the ozonation ahead of biofilters is beneficial. Glover et al () conducted sampling at full‐scale and pilot‐scale ozone/BAC processes for perfluoroalkyl and polyfluoroalkyl substances. Their research concluded that ozone/BAC removed many nontargeted perfluoroalkyl and polyfluoroalkyl substances, but not targeted substances to the extent needed.…”

A performance‐based indicator chemical framework for potable reuse

“…Reuse regulators may choose to leverage federal guidelines or regulations in other jurisdictions when selecting lists of chemicals for Level 2 and should also update these lists based on recent occurrence and toxicity literature. For example, PFAS occur widely in reclaimed water (Glover et al, 2018). PFOA has had a USEPA health advisory level of 70 ng/L, but its potential MCL is still being evaluated (USEPA, 2020a).…”

“…As a result, meprobamate concentrations in the effluent of a WRF in Nevada have declined significantly over the years 2003-2019 at a rate of 24 ng L −1 year −1 (standard error = 3.5 ng L −1 year −1 , n = 152, p-value = 2.1 × 10 −10 ) ( Figure S1). Based on an MRL of 0.6 ng/L (Shoemaker & Tettenhorst, 2018), PFHpA would have met the concentration criterion in three of four reuse systems in Glover et al (2018), so its suitability as a GAC PBI would also be site-specific. However, in contrast to meprobamate, PFHpA concentration is stable or even increasing in ozonation due to the oxidation of polyfluorinated precursors (Pisarenko et al, 2015).…”